//
//  Electron.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 03/01/2016.
//  Copyright 2016 Thomas Harte. All rights reserved.
//

#include "Electron.hpp"

#include "Activity/Source.hpp"
#include "Machines/MachineTypes.hpp"
#include "Configurable/Configurable.hpp"

#include "ClockReceiver/ClockReceiver.hpp"
#include "ClockReceiver/ForceInline.hpp"
#include "Configurable/StandardOptions.hpp"
#include "Outputs/Speaker/Implementation/LowpassSpeaker.hpp"
#include "Processors/6502/6502.hpp"

#include "Storage/MassStorage/SCSI/SCSI.hpp"
#include "Storage/MassStorage/SCSI/DirectAccessDevice.hpp"
#include "Storage/Tape/Tape.hpp"

#include "Machines/Utility/Typer.hpp"
#include "Analyser/Static/Acorn/Target.hpp"

#include "ClockReceiver/JustInTime.hpp"

#include "Interrupts.hpp"
#include "Keyboard.hpp"
#include "Plus3.hpp"
#include "SoundGenerator.hpp"
#include "Tape.hpp"
#include "Video.hpp"

#include <algorithm>

namespace Electron {

template <bool has_scsi_bus> class ConcreteMachine:
	public Activity::Source,
	public ClockingHint::Observer,
	public Configurable::Device,
	public CPU::MOS6502::BusHandler,
	public Machine,
	public MachineTypes::AudioProducer,
	public MachineTypes::MappedKeyboardMachine,
	public MachineTypes::MediaChangeObserver,
	public MachineTypes::MediaTarget,
	public MachineTypes::ScanProducer,
	public MachineTypes::TimedMachine,
	public SCSI::Bus::Observer,
	public Tape::Delegate,
	public Utility::TypeRecipient<CharacterMapper> {
public:
	ConcreteMachine(const Analyser::Static::Acorn::ElectronTarget &target, const ROMMachine::ROMFetcher &rom_fetcher) :
			m6502_(*this),
			scsi_bus_(4'000'000),
			hard_drive_(scsi_bus_, 0),
			scsi_device_(scsi_bus_.add_device()),
			video_(ram_),
			sound_generator_(audio_queue_),
			speaker_(sound_generator_)
	{
		std::fill(std::begin(key_states_), std::end(key_states_), 0);
		for(int c = 0; c < 16; c++) {
			std::fill(std::begin(roms_[c]), std::end(roms_[c]), 0xff);
		}

		tape_.set_delegate(this);
		set_clock_rate(2000000);

		speaker_.set_input_rate(2000000 / SoundGenerator::clock_rate_divider);
		speaker_.set_high_frequency_cutoff(6000);

		::ROM::Request request = ::ROM::Request(::ROM::Name::AcornBASICII) && ::ROM::Request(::ROM::Name::AcornElectronMOS100);
		if(target.has_pres_adfs) {
			request = request && ::ROM::Request(::ROM::Name::PRESADFSSlot1) && ::ROM::Request(::ROM::Name::PRESADFSSlot2);
		}
		if(target.has_acorn_adfs) {
			request = request && ::ROM::Request(::ROM::Name::AcornADFS);
		}
		if(target.has_dfs) {
			request = request && ::ROM::Request(::ROM::Name::Acorn1770DFS);
		}
		if(target.has_ap6_rom) {
			request = request && ::ROM::Request(::ROM::Name::PRESAdvancedPlus6);
		}
		auto roms = rom_fetcher(request);
		if(!request.validate(roms)) {
			throw ROMMachine::Error::MissingROMs;
		}
		set_rom(ROM::BASIC, roms.find(::ROM::Name::AcornBASICII)->second, false);
		set_rom(ROM::OS, roms.find(::ROM::Name::AcornElectronMOS100)->second, false);

		/*
			ROM slot mapping applied:

				* the keyboard and BASIC ROMs occupy slots 8, 9, 10 and 11;
				* the DFS, if in use, occupies slot 1;
				* the Pres ADFS, if in use, occupies slots 4 and 5;
				* the Acorn ADFS, if in use, occupies slot 6;
				* the AP6, if in use, occupies slot 15; and
				* if sideways RAM was asked for, all otherwise unused slots are populated with sideways RAM.
		*/
		if(target.has_dfs || target.has_acorn_adfs || target.has_pres_adfs) {
			plus3_ = std::make_unique<Plus3>();

			if(target.has_dfs) {
				set_rom(ROM::Slot0, roms.find(::ROM::Name::Acorn1770DFS)->second, true);
			}
			if(target.has_pres_adfs) {
				set_rom(ROM::Slot4, roms.find(::ROM::Name::PRESADFSSlot1)->second, true);
				set_rom(ROM::Slot5, roms.find(::ROM::Name::PRESADFSSlot2)->second, true);
			}
			if(target.has_acorn_adfs) {
				set_rom(ROM::Slot6, roms.find(::ROM::Name::AcornADFS)->second, true);
			}
		}
		if(target.has_ap6_rom) {
			set_rom(ROM::Slot15, roms.find(::ROM::Name::PRESAdvancedPlus6)->second, true);
		}

		if(target.has_sideways_ram) {
			for(int c = 0; c < 16; c++) {
				if(rom_inserted_[c]) continue;
				if(c >= int(ROM::Keyboard) && c < int(ROM::BASIC)+1) continue;
				set_sideways_ram(ROM(c));
			}
		}

		insert_media(target.media);

		if(!target.loading_command.empty()) {
			type_string(target.loading_command);
		}

		if(target.should_shift_restart) {
			shift_restart_counter_ = 1000000;
		}

		if(has_scsi_bus) {
			scsi_bus_.add_observer(*this);
			scsi_bus_.set_clocking_hint_observer(this);
		}
	}

	~ConcreteMachine() {
		audio_queue_.lock_flush();
	}

	void set_key_state(uint16_t key, bool isPressed) final {
		switch(key) {
			default:
				if(isPressed)
					key_states_[key >> 4] |= key&0xf;
				else
					key_states_[key >> 4] &= ~(key&0xf);
			break;

			case KeyBreak:
				m6502_.set_reset_line(isPressed);
			break;

#define FuncShiftedKey(source, dest)	\
			case source:	\
				set_key_state(KeyFunc, isPressed);	\
				set_key_state(dest, isPressed);	\
			break;

			FuncShiftedKey(KeyF1, Key1);
			FuncShiftedKey(KeyF2, Key2);
			FuncShiftedKey(KeyF3, Key3);
			FuncShiftedKey(KeyF4, Key4);
			FuncShiftedKey(KeyF5, Key5);
			FuncShiftedKey(KeyF6, Key6);
			FuncShiftedKey(KeyF7, Key7);
			FuncShiftedKey(KeyF8, Key8);
			FuncShiftedKey(KeyF9, Key9);
			FuncShiftedKey(KeyF0, Key0);

#undef FuncShiftedKey
		}
	}

	void clear_all_keys() final {
		std::fill(std::begin(key_states_), std::end(key_states_), 0);
		if(is_holding_shift_) set_key_state(KeyShift, true);
	}

	bool insert_media(const Analyser::Static::Media &media) final {
		if(!media.tapes.empty()) {
			tape_.set_tape(media.tapes.front(), TargetPlatform::AcornElectron);
		}
		set_use_fast_tape_hack();

		if(!media.disks.empty() && plus3_) {
			plus3_->set_disk(media.disks.front(), 0);
		}

		ROM slot = ROM::Slot12;
		for(std::shared_ptr<Storage::Cartridge::Cartridge> cartridge : media.cartridges) {
			const ROM first_slot_tried = slot;
			while(rom_inserted_[int(slot)]) {
				slot = ROM((int(slot) + 1) & 15);
				if(slot == first_slot_tried) return false;
			}
			set_rom(slot, cartridge->get_segments().front().data, false);
		}

		// TODO: allow this only at machine startup?
		if(!media.mass_storage_devices.empty()) {
			hard_drive_->set_storage(media.mass_storage_devices.front());
		}

		return !media.empty();
	}

	ChangeEffect effect_for_file_did_change(const std::string &file_name) const override {
		const auto disk = plus3_->disk(file_name);
		return disk && disk->has_written() ? ChangeEffect::None : ChangeEffect::RestartMachine;
	}

	std::pair<Cycles, uint8_t> run_for_access(const uint16_t address) {
		if(address < 0x8000) {
			return video_.run_until_ram_slot();
		}

		if((address & 0xff00) == 0xfe00) {
			return video_.run_until_io_slot();
		}

		return std::make_pair(Cycles(1), video_.run_for(Cycles(1)));
	}

	forceinline Cycles perform_bus_operation(const CPU::MOS6502::BusOperation operation, const uint16_t address, uint8_t *const value) {
		const auto [cycles, video_interrupts] = run_for_access(address);
		signal_interrupt(video_interrupts);

		cycles_since_audio_update_ += cycles;
		if(cycles_since_audio_update_ > Cycles(16384)) update_audio();
		tape_.run_for(cycles);

		if(typer_) typer_->run_for(cycles);
		if(plus3_) plus3_->run_for(cycles * 4);
		if(shift_restart_counter_) {
			shift_restart_counter_ -= cycles.template as<int>();
			if(shift_restart_counter_ <= 0) {
				shift_restart_counter_ = 0;
				m6502_.set_power_on(true);
				set_key_state(KeyShift, true);
				is_holding_shift_ = true;
			}
		}

		if constexpr (has_scsi_bus) {
			if(scsi_is_clocked_) {
				scsi_bus_.run_for(cycles);
			}
		}

		if(address < 0x8000) {
			if(is_read(operation)) {
				*value = ram_[address];
			} else {
				ram_[address] = *value;
			}
		} else {
			switch(address & 0xff0f) {
				case 0xfe00:
					if(is_read(operation)) {
						*value = interrupt_status_;
						interrupt_status_ &= ~PowerOnReset;
					} else {
						interrupt_control_ = (*value) & ~1;
						evaluate_interrupts();
					}
				break;
				case 0xfe07:
					if(!is_read(operation)) {
						// update speaker mode
						bool new_speaker_is_enabled = (*value & 6) == 2;
						if(new_speaker_is_enabled != speaker_is_enabled_) {
							update_audio();
							sound_generator_.set_is_enabled(new_speaker_is_enabled);
							speaker_is_enabled_ = new_speaker_is_enabled;
						}

						tape_.set_is_enabled((*value & 6) != 6);
						tape_.set_is_in_input_mode((*value & 6) == 0);
						tape_.set_is_running((*value & 0x40) ? true : false);

						caps_led_state_ = !!(*value & 0x80);
						if(activity_observer_)
							activity_observer_->set_led_status(caps_led, caps_led_state_);
					}

					[[fallthrough]];	// fe07 contains the display mode.


				case 0xfe02: case 0xfe03:
				case 0xfe08: case 0xfe09: case 0xfe0a: case 0xfe0b:
				case 0xfe0c: case 0xfe0d: case 0xfe0e: case 0xfe0f:
					if(!is_read(operation)) {
						video_.write(address, *value);
					}
				break;
				case 0xfe04:
					if(is_read(operation)) {
						*value = tape_.get_data_register();
						tape_.clear_interrupts(Interrupt::ReceiveDataFull);
					} else {
						tape_.set_data_register(*value);
						tape_.clear_interrupts(Interrupt::TransmitDataEmpty);
					}
				break;
				case 0xfe05:
					if(!is_read(operation)) {
						const uint8_t interruptDisable = (*value)&0xf0;
						if( interruptDisable ) {
							if( interruptDisable&0x10 ) interrupt_status_ &= ~Interrupt::DisplayEnd;
							if( interruptDisable&0x20 ) interrupt_status_ &= ~Interrupt::RealTimeClock;
							if( interruptDisable&0x40 ) interrupt_status_ &= ~Interrupt::HighToneDetect;
							evaluate_interrupts();

							// TODO: NMI
						} else {
							// Latch the paged ROM in case external hardware is being emulated.
							active_rom_ = *value & 0xf;

							// apply the ULA's test
							if(*value & 0x08) {
								if(*value & 0x04) {
									keyboard_is_active_ = false;
									basic_is_active_ = false;
								} else {
									keyboard_is_active_ = !(*value & 0x02);
									basic_is_active_ = !keyboard_is_active_;
								}
							}
						}
					}
				break;
				case 0xfe06:
					if(!is_read(operation)) {
						update_audio();
						sound_generator_.set_divider(*value);
						tape_.set_counter(*value);
					}
				break;

				case 0xfc04: case 0xfc05: case 0xfc06: case 0xfc07:
					if(plus3_ && (address&0x00f0) == 0x00c0) {
						if(is_holding_shift_ && address == 0xfcc4) {
							is_holding_shift_ = false;
							set_key_state(KeyShift, false);
						}
						if(is_read(operation))
							*value = plus3_->read(address);
						else
							plus3_->write(address, *value);
					}
				break;
				case 0xfc00:
					if(plus3_ && (address&0x00f0) == 0x00c0) {
						if(!is_read(operation)) {
							plus3_->set_control_register(*value);
						} else *value = 1;
					}

					if(has_scsi_bus && (address&0x00f0) == 0x0040) {
						scsi_acknowledge_ = true;
						if(!is_read(operation)) {
							scsi_data_ = *value;
							push_scsi_output();
						} else {
							*value = SCSI::data_lines(scsi_bus_.state());
							push_scsi_output();
						}
					}
				break;
				case 0xfc03:
					if(has_scsi_bus && (address&0x00f0) == 0x0040) {
						scsi_interrupt_state_ = false;
						scsi_interrupt_mask_ = *value & 1;
						evaluate_interrupts();
					}
				break;
				case 0xfc01:
					if(has_scsi_bus && (address&0x00f0) == 0x0040 && is_read(operation)) {
						// Status byte is:
						//
						//	b7:	SCSI C/D
						//	b6: SCSI I/O
						//	b5: SCSI REQ
						//	b4: interrupt flag
						//	b3:	0
						//	b2:	0
						//	b1:	SCSI BSY
						//	b0: SCSI MSG
						const auto state = scsi_bus_.state();
						*value =
							(state & SCSI::Line::Control ? 0x80 : 0x00) |
							(state & SCSI::Line::Input ? 0x40 : 0x00) |
							(state & SCSI::Line::Request ? 0x20 : 0x00) |
							((scsi_interrupt_state_ && scsi_interrupt_mask_) ? 0x10 : 0x00) |
							(state & SCSI::Line::Busy ? 0x02 : 0x00) |
							(state & SCSI::Line::Message ? 0x01 : 0x00);

						// Empirical guess: this is also the trigger to affect busy/request/acknowledge
						// signalling. Maybe?
						if(scsi_select_ && scsi_bus_.state() & SCSI::Line::Busy) {
							scsi_select_ = false;
							push_scsi_output();
						}
					}
				break;
				case 0xfc02:
					if(has_scsi_bus && (address&0x00f0) == 0x0040) {
						scsi_select_ = true;
						push_scsi_output();
					}
				break;

				// SCSI locations:
				//
				//	fc40:	data, read and write
				//	fc41:	status read
				//	fc42:	select write
				//	fc43:	interrupt latch
				//
				//
				// Interrupt latch is:
				//
				//	b0: enable or disable IRQ on REQ
				//	(and, possibly, writing to the latch acknowledges?)

				default:
					if(address >= 0xc000) {
						if(is_read(operation)) {
							if(
								use_fast_tape_hack_ &&
								(operation == CPU::MOS6502::BusOperation::ReadOpcode) &&
								(
									(address == 0xf4e5) || (address == 0xf4e6) ||	// double NOPs at 0xf4e5, 0xf6de, 0xf6fa and 0xfa51
									(address == 0xf6de) || (address == 0xf6df) ||	// act to disable the normal branch into tape-handling
									(address == 0xf6fa) || (address == 0xf6fb) ||	// code, forcing the OS along the serially-accessed ROM
									(address == 0xfa51) || (address == 0xfa52) ||	// pathway.

									(address == 0xf0a8)								// 0xf0a8 is from where a service call would normally be
																					// dispatched; we can check whether it would be call 14
																					// (i.e. read byte) and, if so, whether the OS was about to
																					// issue a read byte call to a ROM despite the tape
																					// FS being selected. If so then this is a get byte that
																					// we should service synthetically. Put the byte into Y
																					// and set A to zero to report that action was taken, then
																					// allow the PC read to return an RTS.
								)
							) {
								const auto service_call = uint8_t(m6502_.value_of(CPU::MOS6502::Register::X));
								if(address == 0xf0a8) {
									if(!ram_[0x247] && service_call == 14) {
										tape_.set_delegate(nullptr);

										int cycles_left_while_plausibly_in_data = 50;
										tape_.clear_interrupts(Interrupt::ReceiveDataFull);
										while(!tape_.serialiser()->is_at_end()) {
											tape_.run_for_input_pulse();
											--cycles_left_while_plausibly_in_data;
											if(!cycles_left_while_plausibly_in_data) fast_load_is_in_data_ = false;
											if(	(tape_.get_interrupt_status() & Interrupt::ReceiveDataFull) &&
												(fast_load_is_in_data_ || tape_.get_data_register() == 0x2a)
											) break;
										}
										tape_.set_delegate(this);
										tape_.clear_interrupts(Interrupt::ReceiveDataFull);
										interrupt_status_ |= tape_.get_interrupt_status();

										fast_load_is_in_data_ = true;
										m6502_.set_value_of(CPU::MOS6502::Register::A, 0);
										m6502_.set_value_of(CPU::MOS6502::Register::Y, tape_.get_data_register());
										*value = 0x60; // 0x60 is RTS
									}
									else *value = os_[address & 16383];
								}
								else *value = 0xea;
							} else {
								*value = os_[address & 16383];
							}
						}
					} else {
						if(is_read(operation)) {
							*value = roms_[active_rom_][address & 16383];
							if(keyboard_is_active_) {
								*value &= 0xf0;
								for(int address_line = 0; address_line < 14; address_line++) {
									if(!(address&(1 << address_line))) *value |= key_states_[address_line];
								}
							}
							if(basic_is_active_) {
								*value &= roms_[int(ROM::BASIC)][address & 16383];
							}
						} else if(rom_write_masks_[active_rom_]) {
							roms_[active_rom_][address & 16383] = *value;
						}
					}
				break;
			}
		}

		return cycles;
	}

	void flush_output(int outputs) final {
		if(outputs & Output::Audio) {
			update_audio();
			audio_queue_.perform();
		}
	}

	void set_scan_target(Outputs::Display::ScanTarget *scan_target) final {
		video_.set_scan_target(scan_target);
	}

	Outputs::Display::ScanStatus get_scaled_scan_status() const final {
		return video_.get_scaled_scan_status();
	}

	void set_display_type(Outputs::Display::DisplayType display_type) final {
		video_.set_display_type(display_type);
	}

	Outputs::Display::DisplayType get_display_type() const final {
		return video_.get_display_type();
	}

	Outputs::Speaker::Speaker *get_speaker() final {
		return &speaker_;
	}

	void run_for(const Cycles cycles) final {
		m6502_.run_for(cycles);
	}

	void scsi_bus_did_change(SCSI::Bus &, const SCSI::BusState new_state, double) final {
		// Release acknowledge when request is released.
		if(scsi_acknowledge_ && !(new_state & SCSI::Line::Request)) {
			scsi_acknowledge_ = false;
			push_scsi_output();
		}

		// Output occurs only while SCSI::Line::Input is inactive; therefore a change
		// in that line affects what's on the bus.
		if(((new_state^previous_bus_state_)&SCSI::Line::Input)) {
			push_scsi_output();
		}

		scsi_interrupt_state_ |= (new_state^previous_bus_state_)&new_state & SCSI::Line::Request;
		previous_bus_state_ = new_state;
		evaluate_interrupts();
	}

	void set_component_prefers_clocking(ClockingHint::Source *, ClockingHint::Preference preference) final {
		scsi_is_clocked_ = preference != ClockingHint::Preference::None;
	}

	void tape_did_change_interrupt_status(Tape &) final {
		interrupt_status_ = (interrupt_status_ & ~(Interrupt::TransmitDataEmpty | Interrupt::ReceiveDataFull | Interrupt::HighToneDetect)) | tape_.get_interrupt_status();
		evaluate_interrupts();
	}

	HalfCycles get_typer_delay(const std::string &text) const final {
		if(!m6502_.get_is_resetting()) {
			return Cycles(0);
		}

		// Add a longer delay for a command at reset that involves pressing a modifier;
		// empirically this seems to be a requirement, in order to avoid a collision with
		// the system's built-in modifier-at-startup test (e.g. to perform shift+break).
		CharacterMapper test_mapper;
		const uint16_t *const sequence = test_mapper.sequence_for_character(text[0]);
		return is_modifier(Key(sequence[0])) ? Cycles(1'000'000) : Cycles(750'000);
	}

	HalfCycles get_typer_frequency() const final {
		return Cycles(60'000);
	}

	void type_string(const std::string &string) final {
		Utility::TypeRecipient<CharacterMapper>::add_typer(string);
	}

	bool can_type(char c) const final {
		return Utility::TypeRecipient<CharacterMapper>::can_type(c);
	}

	KeyboardMapper *get_keyboard_mapper() final {
		return &keyboard_mapper_;
	}

	// MARK: - Configuration options.
	std::unique_ptr<Reflection::Struct> get_options() const final {
		auto options = std::make_unique<Options>(Configurable::OptionsType::UserFriendly);
		options->output = get_video_signal_configurable();
		options->quick_load = allow_fast_tape_hack_;
		return options;
	}

	void set_options(const std::unique_ptr<Reflection::Struct> &str) final {
		const auto options = dynamic_cast<Options *>(str.get());

		set_video_signal_configurable(options->output);
		allow_fast_tape_hack_ = options->quick_load;
		set_use_fast_tape_hack();
	}

	// MARK: - Activity Source
	void set_activity_observer(Activity::Observer *observer) final {
		activity_observer_ = observer;
		if(activity_observer_) {
			activity_observer_->register_led(caps_led, Activity::Observer::LEDPresentation::Persistent);
			activity_observer_->set_led_status(caps_led, caps_led_state_);
		}

		if(plus3_) {
			plus3_->set_activity_observer(observer);
		}

		if(has_scsi_bus) {
			scsi_bus_.set_activity_observer(observer);
		}
	}

private:
	enum class ROM {
		Slot0 = 0,
		Slot1,	Slot2,	Slot3,
		Slot4,	Slot5,	Slot6,	Slot7,

		Keyboard = 8,	Slot9,
		BASIC = 10,		Slot11,

		Slot12,	Slot13,	Slot14,	Slot15,

		OS,		DFS,
		ADFS1,	ADFS2
	};

	/*!
		Sets the contents of @c slot to @c data. If @c is_writeable is @c true then writing to the slot
		is enabled: it acts as if it were sideways RAM. Otherwise the slot is modelled as containing ROM.
	*/
	void set_rom(const ROM slot, const std::vector<uint8_t> &data, const bool is_writeable) {
		uint8_t *target = nullptr;
		switch(slot) {
			case ROM::OS:		target = os_;			break;
			default:
				target = roms_[int(slot)];
				rom_write_masks_[int(slot)] = is_writeable;
			break;
		}

		// Copy in, with mirroring.
		std::size_t rom_ptr = 0;
		while(rom_ptr < 16384) {
			const std::size_t size_to_copy = std::min(16384 - rom_ptr, data.size());
			std::copy(data.begin(), data.begin() + ptrdiff_t(size_to_copy), &target[rom_ptr]);
			rom_ptr += size_to_copy;
		}

		if(int(slot) < 16) {
			rom_inserted_[int(slot)] = true;
		}
	}

	/*!
		Enables @c slot as sideways RAM; ensures that it does not currently contain a valid ROM signature.
	*/
	void set_sideways_ram(const ROM slot) {
		auto &rom = roms_[int(slot)];
		std::fill(std::begin(rom), std::end(rom), 0xff);
		if(int(slot) < 16) {
			rom_inserted_[int(slot)] = true;
			rom_write_masks_[int(slot)] = true;
		}
	}

	// MARK: - Work deferral updates.
	inline void update_audio() {
		speaker_.run_for(audio_queue_, cycles_since_audio_update_.divide(Cycles(SoundGenerator::clock_rate_divider)));
	}

	inline void signal_interrupt(uint8_t interrupt) {
		if(!interrupt) {
			return;
		}
		interrupt_status_ |= interrupt;
		evaluate_interrupts();
	}

	inline void clear_interrupt(Interrupt interrupt) {
		interrupt_status_ &= ~interrupt;
		evaluate_interrupts();
	}

	inline void evaluate_interrupts() {
		if(interrupt_status_ & interrupt_control_) {
			interrupt_status_ |= 1;
		} else {
			interrupt_status_ &= ~1;
		}

		if constexpr (has_scsi_bus) {
			m6502_.set_irq_line((scsi_interrupt_state_ && scsi_interrupt_mask_) | (interrupt_status_ & 1));
		} else {
			m6502_.set_irq_line(interrupt_status_ & 1);
		}
	}

	CPU::MOS6502::Processor<CPU::MOS6502::Personality::P6502, ConcreteMachine, false> m6502_;

	// Things that directly constitute the memory map.
	uint8_t roms_[16][16384];
	bool rom_inserted_[16] = {false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false};
	bool rom_write_masks_[16] = {false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false};
	uint8_t os_[16384], ram_[32768];

	// Paging
	int active_rom_ = int(ROM::Slot0);
	bool keyboard_is_active_ = false;
	bool basic_is_active_ = false;

	// Interrupt and keyboard state
	uint8_t interrupt_status_ = Interrupt::PowerOnReset | Interrupt::TransmitDataEmpty | 0x80;
	uint8_t interrupt_control_ = 0;
	uint8_t key_states_[14];
	Electron::KeyboardMapper keyboard_mapper_;

	// Counters related to simultaneous subsystems
	Cycles cycles_since_audio_update_ = 0;

	// Tape
	Tape tape_;
	bool use_fast_tape_hack_ = false;
	bool allow_fast_tape_hack_ = false;
	void set_use_fast_tape_hack() {
		use_fast_tape_hack_ = allow_fast_tape_hack_ && tape_.has_tape();
	}
	bool fast_load_is_in_data_ = false;

	// Disk
	std::unique_ptr<Plus3> plus3_;
	bool is_holding_shift_ = false;
	int shift_restart_counter_ = 0;

	// Hard drive.
	SCSI::Bus scsi_bus_;
	SCSI::Target::Target<SCSI::DirectAccessDevice> hard_drive_;
	SCSI::BusState previous_bus_state_ = SCSI::DefaultBusState;
	const size_t scsi_device_ = 0;
	uint8_t scsi_data_ = 0;
	bool scsi_select_ = false;
	bool scsi_acknowledge_ = false;
	bool scsi_is_clocked_ = false;
	bool scsi_interrupt_state_ = false;
	bool scsi_interrupt_mask_ = false;
	void push_scsi_output() {
		scsi_bus_.set_device_output(scsi_device_,
			(scsi_bus_.state()&SCSI::Line::Input ? 0 : scsi_data_) |
			(scsi_select_ ? SCSI::Line::SelectTarget : 0) |
			(scsi_acknowledge_ ? SCSI::Line::Acknowledge : 0)
		);
	}

	// Outputs
	VideoOutput video_;

	Concurrency::AsyncTaskQueue<false> audio_queue_;
	SoundGenerator sound_generator_;
	Outputs::Speaker::PullLowpass<SoundGenerator> speaker_;

	bool speaker_is_enabled_ = false;

	// MARK: - Caps Lock status and the activity observer.
	static inline const std::string caps_led = "CAPS";
	bool caps_led_state_ = false;
	Activity::Observer *activity_observer_ = nullptr;
};

}

using namespace Electron;

std::unique_ptr<Machine> Machine::Electron(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
	using Target = Analyser::Static::Acorn::ElectronTarget;
	const Target *const acorn_target = dynamic_cast<const Target *>(target);

	if(acorn_target->media.mass_storage_devices.empty()) {
		return std::make_unique<Electron::ConcreteMachine<false>>(*acorn_target, rom_fetcher);
	} else {
		return std::make_unique<Electron::ConcreteMachine<true>>(*acorn_target, rom_fetcher);
	}
}
